This paper reports a small exploratory study which identifies what community nurses consider to be the scope of their practice and the sources of influence on their clinical decisions. The study was stimulated by the emergence of the nurse prescribing initiative, which is likely to bring clinical decision making to the centre of professional debate. The study was carried out over a 5-month period and data were collected from 47 community nurses in four district health authorities. A qualitative method was employed and field work involved observation of 40 home visits and five nurse-run clinics, individual interviews and group discussions with the nurses, and scrutiny of nursing records. The data were content analysed and classified, and the categories were validated by practitioners. Findings suggest that although community nurses consider that a large proportion of their work requires a scientific basis, their practice is largely founded on experiential knowledge, and on the whole they are not positively disposed to research knowledge. The findings are discussed in the context of nurse prescribing. Questions are raised about the nature of a 'professional' knowledge base and the reclassification of scientific knowledge as nursing or experiential knowledge once it has diffused into practice.